14,178 research outputs found
Alternative scheme for two-qubit conditional phase gate by adiabatic passage under dissipation
We check a recent proposal [H. Goto and K. Ichimura Phys. Rev. A 70, 012305
(2004)] for controlled phase gate through adiabatic passage under the influence
of spontaneous emission and the cavity decay. We show a modification of above
proposal could be used to generate the necessary conditional phase gates in the
two-qubit Grover search. Conditioned on no photon leakage either from the
atomic excited state or from the cavity mode during the gating period, we
numerically analyze the success probability and the fidelity of the two-qubit
conditional phase gate by adiabatic passage. The comparison made between our
proposed gating scheme and a previous one shows that Goto and Ichimura's scheme
is an alternative and feasible way in the optical cavity regime for two-qubit
gates and could be generalised in principle to multi-qubit gates.Comment: to appear in J. Phys.
The Ubiquitin Specific Protease USP34 promotes ubiquitin signaling at DNA double-strand breaks
published_or_final_versio
The double Ringel-Hall algebra on a hereditary abelian finitary length category
In this paper, we study the category of semi-stable
coherent sheaves of a fixed slope over a weighted projective curve. This
category has nice properties: it is a hereditary abelian finitary length
category. We will define the Ringel-Hall algebra of and
relate it to generalized Kac-Moody Lie algebras. Finally we obtain the Kac type
theorem to describe the indecomposable objects in this category, i.e. the
indecomposable semi-stable sheaves.Comment: 29 page
Minimizing engine emissions using state-feedback control with LQR and artificial intelligence fuel estimator
This paper presents a novel engine controller targeting the reduction of gas emissions. Toxic emissions, such as Carbon Monoxide (CO) and Nitric Oxide (NOx) affect the environment and the authorities aim to limit their amount by law. Emissions are formed during the high temperature combustion process, and can be optimised by adjusting some engine operating parameters. In this paper, the model describing emissions output of the engine as a function of engine control parameters is represented as a state-space system. A closed-loop controller is developed by using statefeedback control algorithm. The closed-loop gain, K, is obtained from the LQR tuning principles. The fuel estimator developed in previous works is used in order to reduce the model from the 8th order. The results show that the controller is able to control emission to the minimum in all constraints while keeping engine running in the same performance
SI Engine Simulation Using Residual Gas and Neural Network Modeling to Virtually Estimate the Fuel Composition
Research in electronic controlled internal
combustion engines mainly focuses on improving performance
and lowering the emissions. Combustion performance depends
on the geometry of cylinders and on the design of all
mechanical parts, which are based on the laboratory
experimental research. Due to the limitations of the materials
used in the engine and the continuous high operating
temperature, engines function in either spark ignition or
charge ignition processes. Recent research on computer
controlled engines uses sensors and electronic actuators which
allows switching the engine operational mode between spark
ignition and charge ignition. Thus, this makes possible to mix
intake fuel compositions in order to give more choices to
consumers.
This study employs a neural network which is capable of
estimating fuel composition using the parameters of residual
gas. The simulation is based on a thermodynamic engine model
implemented in Matlab Simulink. The main advantages are the
capabilities of the model to 1) calculate the gas exchange as a
function of time in transient mode, and 2) to generate data for
the design control algorithms without the need of the engine
bed test environment to test various fuel compositions
Using Dynamic Covalent Chemistry To Drive Morphological Transitions: Controlled Release of Encapsulated Nanoparticles from Block Copolymer Vesicles
Dynamic covalent chemistry is exploited to drive morphological order–order transitions to achieve the controlled release of a model payload (e.g., silica nanoparticles) encapsulated within block copolymer vesicles. More specifically, poly(glycerol monomethacrylate)–poly(2-hydroxypropyl methacrylate) (PGMA–PHPMA) diblock copolymer vesicles were prepared via aqueous polymerization-induced self-assembly in either the presence or absence of silica nanoparticles. Addition of 3-aminophenylboronic acid (APBA) to such vesicles results in specific binding of this reagent to some of the pendent cis-diol groups on the hydrophilic PGMA chains to form phenylboronate ester bonds in mildly alkaline aqueous solution (pH ∼ 10). This leads to a subtle increase in the effective volume fraction of this stabilizer block, which in turn causes a reduction in the packing parameter and hence induces a vesicle-to-worm (or vesicle-to-sphere) morphological transition. The evolution in copolymer morphology (and the associated sol–gel transitions) was monitored using dynamic light scattering, transmission electron microscopy, oscillatory rheology, and small-angle X-ray scattering. In contrast to the literature, in situ release of encapsulated silica nanoparticles is achieved via vesicle dissociation at room temperature; moreover, the rate of release can be fine-tuned by varying the solution pH and/or the APBA concentration. Furthermore, this strategy also works (i) for relatively thick-walled vesicles that do not normally exhibit stimulus-responsive behavior and (ii) in the presence of added salt. This novel molecular recognition strategy to trigger morphological transitions via dynamic covalent chemistry offers considerable scope for the design of new stimulus-responsive copolymer vesicles (and hydrogels) for targeted delivery and controlled release of cargoes. In particular, the conditions used in this new approach are relevant to liquid laundry formulations, whereby enzymes require protection to prevent their deactivation by bleach
Fermionic concurrence in the extended Hubbard dimer
In this paper, we introduce and study the fermionic concurrence in a two-site
extended Hubbard model. Its behaviors both at the ground state and finite
temperatures as function of Coulomb interaction (on-site) and
(nearest-neighbor) are obtained analytically and numerically. We also
investigate the change of the concurrence under a nonuniform field, including
local potential and magnetic field, and find that the concurrence can be
modulated by these fields.Comment: 5 pages, 7 figure
Mach-Zehnder Bragg interferometer for a Bose-Einstein Condensate
We construct a Mach-Zehnder interferometer using Bose-Einstein condensed
rubidium atoms and optical Bragg diffraction. In contrast to interferometers
based on normal diffraction, where only a small percentage of the atoms
contribute to the signal, our Bragg diffraction interferometer uses all the
condensate atoms. The condensate coherence properties and high phase-space
density result in an interference pattern of nearly 100% contrast. In
principle, the enclosed area of the interferometer may be arbitrarily large,
making it an ideal tool that could be used in the detection of vortices, or
possibly even gravitational waves.Comment: 10 pages, 3 figures, Quantum Electronics and Laser Science Conference
1999, Postdeadline papers QPD12-
Generalized Morse Potential: Symmetry and Satellite Potentials
We study in detail the bound state spectrum of the generalized Morse
potential~(GMP), which was proposed by Deng and Fan as a potential function for
diatomic molecules. By connecting the corresponding Schr\"odinger equation with
the Laplace equation on the hyperboloid and the Schr\"odinger equation for the
P\"oschl-Teller potential, we explain the exact solvability of the problem by
an symmetry algebra, and obtain an explicit realization of the latter
as . We prove that some of the generators
connect among themselves wave functions belonging to different GMP's (called
satellite potentials). The conserved quantity is some combination of the
potential parameters instead of the level energy, as for potential algebras.
Hence, belongs to a new class of symmetry algebras. We also stress
the usefulness of our algebraic results for simplifying the calculation of
Frank-Condon factors for electromagnetic transitions between rovibrational
levels based on different electronic states.Comment: 23 pages, LaTeX, 2 figures (on request). one LaTeX problem settle
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